In the title compound, C29H21FN2, the phenanthro tricyclic ring system is essentially planar with a maximum deviation of 0.030 (2) Å and makes dihedral angles between of 77.96 (6) and 37.18 (7)° with the dimethylphenyl and fluorophenyl rings, respectively. The crystal packing features weak C-H interactions involving the dimethylphenyl and other phenyl rings.

The derivatives of phenanthroline, which have excellent hole blocking and
electron transporting properties, are likely to have interesting value in the
construction of molecular devices (Yamada et al., 1992).

Indeed, various imidazole derivatives have shown a broad range of
bioactivities, such as antineoplastic, immunosuppressive and
anti-inflammatory activities (Nebert et al., 1987).

The large variety of complexes based on phenanthroline and its derivatives
allows the formation of many different molecular systems with various
applications ranging from metallo-supramolecular chemistry (Lehn et
al., 1996), metal sensors (Walters et al., 2000),
molecular
electronics (Peng et al., 1997) and photo sensitizers (Hara
et
al., 2001).

The molecular structure is shown in Fig.1. The phenanthro tricycle is
essentialy planar. The dihedral angles between phenanthro tricycle to the
dimethylphenyl is 77.96 (6)° and to that of fluorophenyl ring is 37.18 (7)°
respectively.

Further the crystal is stabilized by intermolecular C–H···π interactions
(Table 1), where Cg1 is the centre of gravity of C7/C8/C13/C14/C19/C20 and Cg2
is the centre of gravity of (C8-C13). The symmetry code are: (i)
1/2-x, 1/2+y, 1/2-z.

A mixture of phenanthrene-9,10-dione (1.0 g, 4.8 mmol), ammonium acetate
(1.48 g, 19.2 mmol), 4-fluorobenzaldehyde (0.62 g, 4.8 mmol) and
3,5-dimethyl aniline (3.82 g, 24 mmol) have been refluxed in ethanol (20 ml)
at 353 K. The reaction was monitored by TLC and purified by column
chromatography using petroleum ether : ethyl acetate (9:1) as the eluent.
Yield: 0.78 g (50%). The compound was dissolved in DMSO and allowed to
slow evaporation and single crystals were grown within a period of one week.

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell s.u.'s are taken
into account individually in the estimation of s.u.'s in distances, angles
and torsion angles; correlations between s.u.'s in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted
R-factor wR and goodness of fit S are based on
F2, conventional R-factors R are based on F,
with F set to zero for negative F2. The threshold expression
of F2 > σ(F2) is used only for calculating
R-factors(gt) etc. and is not relevant to the choice of
reflections for refinement. R-factors based on F2 are
statistically about twice as large as those based on F, and
R-factors based on ALL data will be even larger.